Belt conveyors carry cargo materials that may adhere to the endless belt and must be removed during each revolution of the belt in order to maintain efficient operation. Removal is accomplished by applying a cleaner device to the belt, typically either at the discharge end or along the bottom run. Among the known types of cleaners are scrapers and washers, or combinations of these. Depending upon the characteristics of the cargo, known scrapers and washers may perform satisfactorily. However, certain cargos are exceedingly difficult to remove. For example, sludge and similar gelatinous materials can build on a scraper blade until the sludge lifts the blade from the belt, and the blade loses effective operation. In still more difficult circumstances, the sludge may contain long, stringy materials that tend to wrap around a scraper blade and lift it from the belt surface. Such stringy materials not only cause a blade to become ineffective, but because they have wrapped themselves around the blade, their removal may require the attention of a mechanic.
Stringy sludges and similar types of cargo that are difficult to clean from a conveyor belt often are transported on a particular type of conveyor belt that having a physical configuration of convolutions and troughs. Conveyor belts of this type are known as Serpentix belts, because for many years they have been supplied on patented conveyor systems sold under the trademark, Serpentix. In particular, many sludge processing plants find that a troughed, convoluted belt is the most effective choice for moving sludge because a single conveyor can transport the sludge over whatever route is required, despite bends and curves, without a transfer to another belt conveyor. Belts of the Serpentix type are highly desirable in other industrial settings, as well, wherever a load must be carried through a horizontal corner or serpentine pathway. The advantage of using only one conveyor instead of multiple conveyors can be substantial. When transporting an adherent cargo such as sludge, any transfers would be undesirable and could compound the inherent problems with the cargo. Another advantage is that a convoluted, troughed belt can carry a larger load than an equivalent flat belt and is more effective than a flat belt in retaining its load. The convolutions and troughs additionally are helpful in retaining the load against back flow, loss or spillage through vertical or horizontal curves.
Two examples in patent art show belt cleaners that use compound systems in order to extend the effectiveness of belt cleaning operations. U.S. Pat. No. 4,795,024 to Eatwell discloses a conveyor belt scraper unit that has two pairs of arms, one pair operating on each side of a conveyor belt. A first pair carries a scraper blade that is applied to a face of a flat belt, while the second pair carries a reaction roller that acts against the back side of the flat belt in opposition to the scraper blade. A spring acts between the blade and roller to urge together the two components. This unit resists separation between the blade and belt, although a sufficiently difficult, stringy, sludge-like cargo still will overcome the spring force as the stringy elements wrap the blade.
U.S. Pat. No. 4,860,883 to Knaul et al. discloses a conveyor belt cleaning apparatus in which both a powered cleaning roller and a scraper blade engage the bottom of a conveyor belt. Nozzles spray fluid on the cleaning roller to supply cleaning fluid for application to the belt. A pressure roller squeezes excess fluid from the cleaning roller, while a scraper blade, located downstream from the cleaning roller, removes residual fluid and dirt from the belt. This apparatus is effective in situations where the cleaning roller is capable of substantially cleaning the belt. However, sludges can be far too thick and difficult to be handled by such a cleaning roller, which would all too soon become coated with sludge coating that would clog the operation of the entire apparatus.
Thus, there is a substantial need for a conveyor belt cleaning device that can remove adherent stringy materials from a conveyor belt and remain effective despite the tendency of such stringy materials to build up and wrap around the cleaning device.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the apparatus and method of this invention may comprise the following.